Chemical compounds and process for the preparation thereof



2,996,525 CHEMICAL COMPOUNDS AND PROCESS FOR THE PREPARATION THEREOF William S. Barnhart, Crawford, and Robert H. Wade, West Paterson, N.J., assignors, by mesne assignments, to Minnesota Mining and Manufacturing Company, St. Paul, Minn., a corporation of Delaware No Drawing. Original application Apr. 4, 1955, Ser. No. 499,250. Divided and this application Dec. 5, 1958, Ser. No. 789,467

9 Claims.

This invention relates to novel perchlorofluorocarboxylic acid halides, and to a process for the preparation thereof.

In accordance with the present invention, noxel perchlorofluorocarboxylic acid halides are produced by halogenating perchlorofluorocarboxylic acids. Among the halogenating agents which may be used arephosphorus tnichloride, phosphorus pentachloride, oxalyl chloride, phosphorus tribromide, thionyl bromide, and the similar fluorinating or iodinating agents. The acid fluorides, bromides, and iodides may also be prepared using a halogen exchange reaction of the acid chloride with hydrogen fluoride, hydrogen bromide, or hydrogen iodide.

The most important of these compounds are the perchlorofluorocarboxylic acid chlorides, and when these compounds are prepared by reacting a perchlorofluorocarboxylic acid with phosphorus tn'chloride, the phos: phorus trichloride is present in a quantity of 0.3 to 1 mole per mole of the monoacid. Where diacids are used, 0.6 to 2 moles of the phosphorus trichloride are used per mole of the diacid. The quantity of phosphorus trichloride is correspondingly increased for each additional carboxyl group present in the acid, where polycarboxylic acids are used. When phosphorus pentachloride is used, it is present in a quantity of 1 to 1.5 moles per mole of the monoacid and is present in a quantity of 2 to 3 moles per mole of the diacid, with a corresponding increase for each additional carboxylic acid group present. When oxalyl chloride is used, it is present in a quantity of 1 to 3 moles per mole of the monocarboxylic acid and is present in a quantity of 2 to 6 moles per mole of the dicarboxylic acid. In the preparation of the acid fluorides, bromides, and iodides, a quantity of ttiuorinating, brominating, and iodinating agent equivalent to 1 to 3 moles per mole of the monocarboxylic acid is used, with this quantity being correspondingly increased, as above, for each additional polycarboxylic acid present inthe acid which is treated.

The perchlorofluorocarboxylic acids used in the method of this invention may be either monoor polycarboxylic acids containing from about 4 to about 20 carbon atoms.

The perchlorofluorocarboxylic acids which may be used may be prepared in avariety of ways. For. example, they may be produced by subjecting perhalogem ate'd aliphatic olefins having at least 7 carbon atoms and being at least half fiuorinated to oxidation conditions in the presence of a vigorous oxygen-containingoxidation reagent, such as free oxygen in the presence of ultraviolet light, free oxygen in the presence of ultraviolet light and elemental chlorine, free oxygen in the presence of elemental fluorine, and permanganate salts in a liquid medium. Preparation of the acids according to this method is disclosed in copending application Serial No. 452,706, filed August 27, 1954. g

The acids may also be prepared by subjecting aliphatic perhalogenated high polymers to thermal cracking conditions to produce lower molecular weight materials having molecular weights in the oil or wax range and subjecting these materials to oxidation at a temperature not nited States Patent C) higher than about 10 C. in the presence of a permanganate salt in a liquid medium. Processes of this type are disclosed in copending application Serial No. 452,704, fi led August 27, 1954, now Patent No. 2,950,300.

Another method for the preparation of perchlorofl-uorocarboxylic acids, which are useful in the present invention, comprises treating fluorine-containing telomers, having the formula M Br in which M is a perhallomethyl radical having a total atomic weight not higher than 146.5, X and X are fluorine or chlorine atoms, and n is an integer from 2 to 16, with fuming sulfuric acid at a temperature of at least 125 C. This process produces carboxylic acids having the formula telogen, the preferred telomer being the telomerization product of chlorotriiluoroethylene and sulfuryl chloride. The hydrolyzed telomer has the formula in which Z is a carboxylic acid radical or a perhalomethyl,

radical in which all the halogen atoms are fluorine or chlorine and n is an integer from 2 to 16. The preparation of these acids is disclosed in copending application Serial No. 452,705, filed August 27, 1954, now U.S. 2,806,866.

The reaction temperature employed in the process of the present invention may be between about 20 and 100 C. and is preferably between about 30 and 60 C. At the completion of the reaction, when phosphorus pentachloride is used as the chlorinating agent, the temperature is raised to about 210 C. in order to boil off the phosphorus oxychloride by-product formed during the reaction.

agent, such as phosphorus pentachloride, and the reac-' tion is run to completion for a time which may be between a few minutes and about two hours. Generally, the reaction is complete within one hour.

The acid halides produced by the process of the present invention are particularly useful as intermediates in the preparation of important derivatives of perchloroiiuorocarbozxylic acids, such as esters, amides, alcohols, and the like. One example of the use of the acid chlorides, i.e;,

the conversion of the acid chlorides to esters, is disclosed in copending application Serial No. 493,554, filed March 10, 1955, now Patent No. 2,856,388. The acid halides are also useful as bonding agents for-halocarbonpoly mers and as cross-linking agents.

Phosphorus 3 The invention will be further illustrated by reference to the following specific examples:

EXAMPLE 1 Preparation of 01 cF,oFc1 ,cF,coc1

A215 gram portion of Cl(CF CFCl) OF COOI-I was added slowly to phosphorus pentachloride (185 grams, 1.5 0.59 mole) in a round bottom flask fitted with a reflux condenser. After the initial vigorous HCl evolution had ceased, the mixture was heated gently for 2 hours. Pentane (300 ml.) was added to the cooled solution to lessen PO1 solubility and the mixture was filtered. The product was distilled to give a 96 percent yield of acid chloride, B.P. 179.5 C.

EXAMPLE 2 Preparation of Cl(CF CFCl) CF COCl Phosphorus pentachloride (407 grams; 1.95 moles) was added over a one-half hour period to 960 grams (2.0 moles) of Cl(CF CFCl) CF COOH in a 3 liter flask fitted with a CaCl tube. There was a vigorous evolution of HCl but the reaction temperature did not exceed 42 C. After heating for 1 hour on the steam bath, P001 was removed by heating the flask gradually to 205 C. The clear liquid was transferred to a 1 liter flask and distilled under reduced pressure to give 94 grams of telomer acid (0.2 mole) and 878 grams (1.76 moles; 90 percent) of a clear, colorless liquid, B.P. 145 C./ 50 mm.; n =1.3964; d :1.860.

Analysis-Calculated for C OCl F hydrolyzable Cl, 7.1 percent; N.E.=249.2. Found: hydrolyzable Cl, 6.5; N.E.=2.47.

EXAMPLE 3 Preparation of Cl( CF OFCl) CF COCl Phosphorus .pentachloride (2268 grams; 10.9 moles)- was added in portions with stirring to 5420 grams (11.3 moles) of Cl(CF CFCl) CF COOH in a 12 liter threenecked flask, provided with a stirrer, a CaCl tube, and a HCl trap. The mixture was stirred mechanically for 20 minutes after the final addition of PCl The clear solution was transferred to a 5 liter distilling flask and heated until the pot temperature reached 200 C.; 1405 grams of POCl were obtained. An additional 248 grams of forerun were collected at reduced pressure. The product was distilled through a 12 inch Vigreux column, B.P. 145 C./50 mm. The yield, based on PCl was 5147.5 grams (10.3 moles; 94.5 percent).

I EXAMPLE 4 Preparation of Cl(CF OFCl) CF COBr A mixture of phosphorus tribromide (1 mole) and Cl(OF CFCl) OF COOH (3 moles) is heated to 150 C. for 3 hours in a flask fitted with a CaCl tube and a condenser. The crude product layer is then separated and phosphoric acid is removed by extraction with hexane. The product is distilled to give pure Cl(OF OFCl) CF COBr in 90 percent yield.

EXAMPLE 5 Preparation of BrOC(CF CFCl) COBr A mixture of phosphorus tribromide (1 mole) and HOOC(CF CFCl) COOH (6 moles) is heated to 150 C. for 5 hours in a flask fitted with a CaC1 tube and a condenser. The crude product layer is separated, the phosphoric acid is removed by extraction with hexane, and the crude product is distilled to give Br0C(OF CFCl) COBr in 90 percent yield.

r 4 EXAMPLE 6 Preparation of Cl(OF CFCl) CF COF Gaseous HF is bubbled through Cl (CF OFCI) CF COCl GIwFr-CFOmOFrii-Br 2. A compound having the formula Bri 3(CF,-CFC1),(JBr 3. An acid bromide of a perchlorofluorodicarboxylic acid, said acid having the structure in which n is an integer from 2 to 16.

4. An acid bromide of a perchlorofluorocarboxylic acid, said acid having the structure in which n is an integer from 2 to 16.

5. An acid bromide of a perchlorofluorocarboxylic acid selected from the group consisting of in which n is an integer from 2 to 16, and Z and Z; are selected from the group consisting of chlorine and a carboxylic acid radical.

6. An acid bromide of a perchlorofluorodicarboxylic acid, said acid having the structure in which n is an integer from 2 to 16.

7. A process for the preparation of perchlorofluorocarboxylic acid bromides which comprises reacting a brominating agent selected from the group consisting of phosphorus bromide and thionyl bromide with a perchlorofluorocarboxylic acid selected from the group consisting of in which n is an integer from 2 to 16 and Z and Z; are selected from the group consisting of chlorine and a carboxylic acid radical.

8. The process of claim 7 in which the brominating agent is phosphorus tribromide.

9. The process of claim 7 in which the brominating agent is thionyl bromide.

and

References Cited in the file of this patent UNITED STATES PATENTS 2,502,478 Padbury et a1 Apr. 4, 1950 2,567,011 Diesslin et al. Sept. 4, 1951 2,704,776 La Zerte Mar. 22, 1955 2,712,554 Miller July 5, 1955 2,717,871 Scholberg et a1. Sept. 13, 1955 

5. AN ACID BROMIDE OF A PERCHLOROFLUOROCARBOXYLIC ACID SELECTED FROM THE GROUP CONSISTING OF Z1(CF2CFC1)N-1CF2COOH AND Z2CFC1(CF2CFC1)N-2CF2COOH IN WHICH N IS AN INTEGER FROM 2 TO 16, AND Z1 ANS Z2 ARE SELECTED FROM THE GROUP CONSISTING OF CHLORINE AND A CARBOXYOIC ACID RADICAL.
 6. AN ACID BROMIDE OF A PERCHLOROFLUORODICARBOXYLIC ACID, SAID ACID HAVING THE STRUCTURE HOOC-CFC1(CF2-CF1)N-2CF2COOH IN WHICH N IS AN INTEGER FROM 2 TO
 16. 